System and Method for Using Capacitors in Wireless Networks

ABSTRACT

A battery-free wireless network is provided with one or more series or parallel capacitive networks. One or more solar panels are used to charge the capacitive networks and one or more charging circuits are used to control the charging of the capacitive networks. One or more DC-DC converters maybe used to provide a voltage to a wireless router, switch or other network device, the timer/clock circuitry, and a user interface. In those instances when it is desired that the timer/clock circuitry remain powered at all times, the timer/clock circuitry is preferentially preserved at the expense of the network device such that if, for any reason, the capacitive network is drained after running the network device, there will still be sufficient power stored in the capacitive network to maintain the timer/clock circuitry.

PRIORITY STATEMENT UNDER 35 U.S.C. §119 & 37 C.F.R. §1.78

This non-provisional application claims priority based upon prior U.S.Provisional Patent Application Ser. No. 61/433,833 filed Jan. 18, 2011in the name of William P. Laceky, Marty Akins, William Bryant and BryanLee entitled “Battery-Free Methods and Systems,” the disclosure of whichis incorporated herein in its entirety by reference as if fully setforth herein.

BACKGROUND OF THE INVENTION

There are an extremely wide variety of products used or useful in thewireless networking industry that utilize batteries or solar cells/solarpanels or a combination of both batteries and solar panels to power theproducts. However, in many cases, the batteries are a major cause offailure and maintenance. A product that uses only batteries without asolar charging device will require the end user to periodically chargeor change the battery. Even batteries charged by solar cells or solarpanels will require user maintenance due to the inherent limitations ofbatteries that cause the battery to degrade and fail over time, inaddition to the influence of many other factors such as temperature,charge rate, depth of discharge, vibration, etc. Depending on the dutyof the product, the user may have to recharge the battery anywhere fromdaily to yearly. A device that uses solar cells/solar panels along withbatteries typically requires less maintenance since the solar energy isused to charge the batteries during the day and the batteries power theelectrical circuit at night. This cycle helps keep the battery fromcompletely discharging, reducing user charging or changing maintenance.However, the physical properties of batteries are such that the batteryis typically limited to several hundred recharging cycles. Moreover, thenumber of recharging cycles is negatively affected by variations of theambient temperature surrounding the batteries. Since these products aredesigned for use in an outdoor environment where the batteries areexposed to extreme cold and hot conditions, the batteries typicallyreach an early end of life ranging from days to several years dependingon their usage and environmental surroundings.

The present invention provides several advantages over the prior artincluding: a longer life compared to systems that rely on rechargeablebatteries; the reduction or elimination of battery maintenance; alighter weight system; superior temperature tolerance; almost unlimiteduse (charging and discharging); and a system that is moreenvironmentally friendly than battery-based systems.

Those skilled in the art can readily determine the voltage at givenpoints in time during the discharging or charging of the capacitors. Thecapacitors would be discharging due to the load presented by theproducts function being powered by the capacitors. The capacitors can becharging under various conditions and circumstances depending on theproduct's intended function, design, type of charging power source, andhow much charging energy is available from the source at any given time.(an example of capacitor discharging would be power required from thecapacitor(s) to power the control circuitry of the device). To maximizethe energy stored in these capacitors, a DC to DC converter can be usedto step the capacitor voltage up or down to obtain a steady power supplyfor the device as the capacitor voltages drop. For example, a DC to DCcharge-pump or switch-mode circuit could be used to convert the 6Vcapacitor voltage to 6V DC even as the capacitor voltage falls below 6volts. This provides the maximum amount of energy from the capacitors tobe used for powering the device circuits, allowing the designer tominimize the number of capacitors used in the design while maintainingthe appropriate duration of available power between re-charges from thesolar panel.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a battery-free wirelessnetwork is adapted with one or more series or parallel capacitivenetworks. One or more solar panels are used to charge the capacitivenetworks and one or more charging circuits are used to control thecharging of the capacitive networks. One or more DC-DC converters maybeused to provide a voltage to a wireless router, switch or other device,the timer/clock circuitry and a user interface. In those instances whenit is desired that the timer remain powered at all times, the controlcircuitry is preferentially preserved at the expense of load such thatif, for any reason, the capacitive network is drained after running theload, there will still be sufficient power stored in capacitive networkto maintain the control circuitry needed to maintain the desiredoperation of the system.

The foregoing has outlined rather broadly certain aspects of the presentinvention in order that the detailed description of the invention thatfollows may be better understood. Additional features and advantages ofthe invention will be described hereinafter which form the subject ofthe claims of the invention. It should be appreciated by those skilledin the art that the conception and specific embodiment disclosed may bereadily utilized as a basis for modifying or designing other structuresor processes for carrying out the same purposes of the presentinvention. It should also be realized by those skilled in the art thatsuch equivalent constructions do not depart from the spirit and scope ofthe invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1 is a block diagram showing a basic depiction of a system usingcapacitive energy storage in place of battery energy storage;

FIG. 2 is a diagram showing a network configuration utilizing variousembodiments of the apparatus of the present invention;

FIG. 3 is a block diagram of an system used to power a wireless networkdevice of the present invention;

FIG. 4 is a block diagram of an example of a wireless network deviceusing capacitive energy storage;

FIG. 5 is a block diagram showing another embodiment of a system forpowering a wireless network device of the present invention;

FIG. 6 is a block diagram illustrating circuitry for powering a wirelessnetwork device and for powering other circuitry using energy stored incapacitive networks;

FIGS. 7 and 8 are block diagrams illustrating other embodiments of thepresent invention;

FIG. 9 is a block diagram of another example of a system for poweringwireless network device using capacitive energy storage; and

FIG. 10 is a block diagram of another example of a system for powering awireless network device using capacitive energy storage.

DETAILED DESCRIPTION OF THE INVENTION

The present invention contemplates systems powered by energy stored incapacitors. For example, a system may include a device that draws powerfrom one or more capacitors. In this example, energy stored in thecapacitors comes from one or more power supplies. If desired, the systemcan be operated without batteries, which may increase the reliabilityand life span of the system. The present invention may be used with anydevice that requires a power source for providing power to a powerdissipating devices. The invention may be used for applications beyondthose set forth in this application, as persons of ordinary skill in theart who have the benefit of the description of the invention willunderstand.

The present invention includes a power storage module using one or morecapacitors to store energy. As discussed above, one of the problems withprior art systems is that batteries fail in a relatively short amount oftime and require more difficult recharging efforts. The power storagemodule of the present invention solves this problem with theintroduction of capacitive storage. The capacitors used in thisinvention have a much longer life expectancy than batteries and are mucheasier to charge. Thus, this invention requires a smaller and lessexpensive solar panel than other comparable battery operated and solarcharged devices. Also, the capacitors can be discharged completelywithout any negative effect, whereas batteries typically cannot bedischarged below 80% of their capacity without damage.

FIG. 1 is a basic depiction of a system 10 using capacitive energystorage in place of battery energy storage. FIG. 1 shows a capacitivenetwork 12, which is coupled to solar panel 14. The capacitive networkmay be comprised of a single capacitor or multiple capacitors. Multiplecapacitors could be placed in series, parallel, or in a series-parallelconfiguration. These configurations could exist as a singleconfiguration or as multiple configurations depending on the voltage andcurrent requirements of the operating circuit. FIG. 1 also shows controlcircuitry 16 and a load 18 coupled to the capacitive network 12 andsolar panel 14. The control circuitry 16 may include circuitry tocontrol the operation of the load, as well as circuitry to control thecharging and discharging of the capacitive network 12.

Capacitor technology using high dielectric films such as, but notlimited to “Aerogel” allow large amounts of energy storage to exist inrelatively small packages. Capacitors have a much greater (almostinfinite) number of charge and discharge cycles compared to batteries.Capacitors are also far less affected by temperature. Using the conceptstaught by the present invention, the density of the energy storage ofcapacitors allows adequate energy storage in capacitor form to replacebatteries in many devices. Given the longer life properties ofcapacitors, devices using capacitors instead of batteries dramaticallyreduce required user maintenance. The network devices contemplatedherein use capacitors in place of batteries along with an adequate powersupply, such as solar cells/solar panels, to repeatedly charge thecapacitors during the day so they can be left unattended for yearswithout maintenance.

While a person skilled in the art could utilize numerous storage modulesusing capacitors, following are some general guidelines for usingcapacitors in the products contemplated herein. Typically, capacitorshave a working voltage that should not be exceeded. Capacitors also havean internal series resistance that may be taken into account along withthe current demand that will be put on them. Capacitors can be connectedin series to increase the stored voltage capability of the network. Aseries connection comes at the expense of decreasing the capacitance(Farads) of the network. Capacitors, or series strings of capacitors,can be connected in parallel to increase the capacitance value of theoverall network. It may be necessary to balance the capacitors in seriesor in a series/parallel combination to, among other things, counteractthe effects of variance in capacitance and leakage current and protectthe capacitors from overvoltage. Balancing capacitors in series can bedone in several ways, for instance, passively or actively. Passively,requires an appropriate sized load be placed permanently in parallelwith each capacitor to be balanced. Placing a resistor across eachcapacitor would be a passive way to keep the voltages balancedreasonably equally from one capacitor to another. However, this methoddoes not protect well against overvoltage of the capacitors. This methodalso presents a load to the circuit which continuously drains thecapacitors. In most cases this is undesirable. In some applications, itmay be desirable or imperative to provide balancing and overvoltageprotection that is much faster and more accurate than passive methods.In this case active control is necessary. This can be done in severalways. One method but certainly not the only method would be to sense thevoltage across each capacitor individually, then making a logicaldecision as to whether the voltage is too high or too low or in anacceptable range. In this example, a load can be turned ON or OFF inparallel with the capacitor of interest. Turning ON a parallel loadallows energy to be drained out of the capacitor. Turning OFF the loadallows the capacitor to continue to build charge. The parallel load canbe adjusted by design to create an appropriately sized load to achievethe balance required within a specific amount of time. The ability toturn this load ON/OFF conserves energy until excess energy is present,making it a very efficient method to balance and maintain voltage levelsacross individual capacitors in a series or series/parallel string.

It is important to note that one cannot simply replace a battery with acapacitor and be able to effectively operate most battery operatedproducts. Capacitors have many differences that require technologyadvances and significant engineering skills and design work toeffectively use them in place of batteries.

One significant difference between batteries and capacitors is theirenergy densities and discharge characteristics. Batteries typically havea flat voltage level as they discharge to the end of their capacity.Capacitors have a different discharge profile, where the voltage fallsquickly at first then slowing as it is discharged to the end of itscapacity. So, for example, a 6V battery used to run a 6V motor in adevice will provide a good steady 6V to the device through most of itscharge without any additional help. On the other hand, a capacitor orcombination of capacitors charged to 6V running the same device willquickly fall to 4V, then 2V, then 1V, etc., as it reaches the end of itscharge. A 6V motor, for example, will not run very well, if at all, withthese low voltages. The circuitry of the present invention overcomesthese problems, allowing the device to run on capacitors.

Energy density also presents a major challenge when trying to replacebatteries with capacitors. Batteries may have much more stored energythan capacitors. For example, a lead acid battery might run a 6V, 3 Adevice for a couple of hours. A capacitor of similar cost to the batterymight only be able to run that device for a few seconds before runningout of energy. The capacitor alone would not be able to even do thiswithout specially designed conversion circuitry that efficiently takesmost of the usable energy in the capacitor and converts it into usableenergy for the device.

In many cases, one power consuming device attached to the capacitors,such as a clock or control circuitry, preferably should be able to runindefinitely (without power interruption) for years without interventionor help from anyone. It must be able to do this with the only energysource to charge it, such as solar energy through a solar panel(photovoltaic). The product should achieve this through periods ofdarkness (due to nighttime and days of heavy cloud cover, rain, andsnow). Likewise, another power consuming device attached to thecapacitors should preferably be able to run at a constant energy drawfor a finite amount of time each day in these same conditions.Consequently, there are significant design challenges in order toachieve this performance.

Returning now to FIG. 1, which also shows the connection of an externalpower source 20, which may be used in addition to the solar panel, or asan alternative method, for charging the capacitive network 12. Theexternal power source 20 may include an external charger, batteries,solar panels, solar collectors, wind generators, wave action generators,electrolyzers, fuel cells, piezo electric films or elements orgenerators, AC/DC motors and generators and other power generation orstorage devices.

Alternatively, a manual power source could be included such as, forexample, oscillating a magnet through a coil of wire by shaking togenerate electricity for charging the capacitor. More specifically, ahollow elongated barrel may be disposed within a housing, a wire coilwrapped around the barrel and disposed between the barrel and thehousing, a magnet may be disposed within the barrel and sized to freelyoscillate within the barrel when the barrel is shaken. In oneembodiment, two springs are attached within the barrel and at either endof the barrel to cause the magnet to recoil when the magnet strikes thesprings. The magnet oscillates within the barrel when the barrel isshaken, causing the magnet to pass back and forth through the wire coil,thereby causing current to flow within the coil and providing power tothe capacitors.

Also, it is important to note that in many of the examples shown below,a DC-DC converter is included between the capacitors and the load. Thoseskilled in the art will realize that it will not always be necessary toinclude a DC-DC converter and in other cases other convertors or devicesto accommodate the specific capacitor configuration and loadrequirements.

The wireless networks, or data communication networks, of the presentinvention may include various network elements, including hubs,switches, routers, and other network devices, interconnected andconfigured to handle data as it passes through the network. Data iscommunicated through the data communication network by passing protocoldata units such as packets, cells, frames, or segments, between thenetwork elements by utilizing one or more communication links. Aparticular packet may be handled by multiple network elements and crossmultiple communication links as it travels between its source and itsdestination over the network. Links may be formed over physicalstructures, such as copper cables and optical fibers, or over wirelesslinks formed using transmissions in a portion of the electromagneticspectrum or infra-red transmissions.

In many cases, it may be desirable to transmit data wirelessly acrosslocations in which power is not readily available for network elements.For example, a rancher may wish to have wireless access available acrossall or a part of a ranch. However, since the network elements requiredto create the wireless network must be placed in locations without powerand each of the network elements requires power to operate, it is notfeasible to have power placed at each required location.

In one embodiment of the present invention, power can be provided toeach of the network elements using solar power coupled with capacitors.In other cases, it may be desirable to have certain functionality ofeach network element receive and maintain power, even when the poweravailable in the capacitors is insufficient to power otherfunctionality. For example, it may be important to keep the device'scontrol circuitry or the dynamic memory cache powered, even though theswitch or the router may not have sufficient power to operate.

An invention in this area that would be advantageous to ranchers orlarge land owners would be a wireless gate sensor that would monitor theOPEN or CLOSED status of gates around the property. An array of wirelesstransmitters/Receivers could be placed virtually anywhere across theproperty (in trees, fence posts, etc.) with such spacing to allowsuccessful communication between them. The arrangement in space would besuch that a network would be created so that any gate anywhere on theproperty would be able to send a signal wirelessly to anothertransceiver device. That transceiver would in turn send the data toanother transceiver. This essentially would be a hopping function suchthat the data from any gate would have a wireless network pathultimately capable of reaching a final destination such as the rancher'shome. In this way, the rancher could be notified at home and becomeaware of anyone opening any gate on a vast property in real time. Thesensors could also identify which gate was opened by transmitting theunique ID of each gate so that the rancher knows for example gate #3 wasopened on the south side of the ranch. Such a network would not besuitable for large networks if each transceiver has to rely onbatteries. The maintenance to change out each network would be veryinconvenient and costly. However, by using a capacitive bank and solarpanel to charge the capacitor(s) at each network node (transceiver), thenetwork could be maintenance free and last virtually indefinitelywithout user interaction.

In another embodiment, a power source, such as a solar panel, may beconnected to one or more capacitors which provide power to the networkelement. The network element may contain a timer or clock circuitry to,for example, control the periods during which the network element isactive or a small power supply to maintain dynamic caching. In oneembodiment, a first DC-DC converter provides a voltage to the clockcircuitry or cache and a second DC-DC converter provides a voltage tothe remaining features of the network element. In this system, it isdesired that the circuitry or the cache remain powered at all times. If,for some reason, the capacitive network is completely drained afterrunning the network element, there will still be sufficient power storedin the capacitive network to maintain the control circuitry or thecache. Separate solar panels may be used to help ensure that there isplenty of energy available from sunlight during cloudy days to fullycharge both capacitor banks. If desired, a battery could be used as abackup power source in the event that energy stored in the capacitors isdepleted. A single solar panel and single capacitor bank could also beused to power the network element. Various other methods of configuringthe network elements with a power source, capacitors and controlcircuitry are described below and referenced in the Figures.

Referring now to FIG. 2, showing one embodiment of a wireless network ofthe present invention. Modem 22 is connected to the Internet and Router24 is connected to modem 22. Router 24 is wirelessly connected to accesspoint 25 which is connected to solar panel 23. Access point 25 is alsowirelessly connected to access point 26 which is connected to solarpanel 28. Device 27 communicates through access point 26, through accesspoint 25, through router 24 through modem 22 to the Internet. Similarly,device 29 communicates through access point 25, through router 24through modem 22 to the Internet. Access point 25 and access point 26are each powered by the capacitive system of the present invention.However, while only the access points are shown as powered by thecapacitive system of the present invention, other devices shown in thenetwork, such as the modem and the router could also be powered by thecapacitive system of the present invention and, in addition, devices notshown in the network, such as switches and hubs, may could also bepowered by the capacitive system of the present invention.

The power that is stored capacitively and provided to one or more loadsin each of the foregoing devices and systems may be provided in avariety of ways. For example, FIG. 3 is a block diagram of oneembodiment of system of the present invention. The system 30 includes aseries/parallel capacitive network 32, such as the network describedabove. A solar panel 34 is used to charge the capacitive network 32,although any power source previously described could be used. A chargingcircuit 36 (described in detail below) is used to control the chargingof the capacitive network 32. A DC-DC converter 38 is used to step thecapacitor voltage up or down to obtain a steady power supply for thedevice as the capacitor voltages drop. The DC-DC converter provides avoltage to both the timer/clock circuitry 40 and the load 42. FIG. 2also shows a user interface block 44, which may include a display,lights, switches, keypad, etc., for use by a user to control theoperation of the system 30.

FIG. 4 is similar to the example shown in FIG. 3, except that a separateDC-DC converter is used by the load 42, which is a power distributioncircuit. In this embodiment, the power distribution circuit providespower to access point 18. FIG. 4 also shows a user interface block 44,which may include a display, lights, switches, keypad, etc., for use bya user to control the operation of the system 30.

FIG. 5 is a block diagram showing another embodiment of the system.

FIG. 5 shows a block diagram of a system 50 that is similar to thesystem shown in FIG. 3, with separate capacitive networks and solarpanels for the load and control circuitry. The system 50 includes firstand second series/parallel capacitive networks 32A and 32B. First andsecond solar panels 34A and 34B are used to charge the capacitivenetworks 32A and 32B, respectively. Charging circuits 36A and 36B areused to control the charging of the capacitive networks 32A and 32B,respectively. A first DC-DC converter 38A provides a voltage to thetimer/clock circuitry 40 and user interface 44. A second DC-DC converter38B provides a voltage to the load. By separating the source of power toload and the control circuitry, the reliability of the system isincreased. In many systems, it is desired that the timer remain poweredat all times. If, for some reason, the capacitive network 32B iscompletely drained after running the load 42, there will still besufficient power stored in capacitive network 32A to maintain the timersand clocks needed to maintain the desired operation of the system.Without this separation, the load 42 could rob the timer of neededenergy. Separate solar panels help ensure that there is plenty of energyavailable from sunlight during cloudy days to fully charge bothcapacitor banks. If desired, with either embodiment, a battery could beused as a backup power source in the event that energy stored in thecapacitors is depleted.

FIG. 6 is a block diagram illustrating circuitry for powering a load andfor powering other circuitry using energy stored in capacitive networks.Like in FIG. 5, in the example shown in FIG. 6, separate solar panelsand capacitive networks are used to power the load and other circuitry.FIG. 6 shows first and second solar panels 100 and 102 that providepower to charge control circuits 104 and 106, respectively. The solarpanels 100 and 102 are ideally sized to provide enough charge (under lowlight) to run the motor or control circuitry for a desired time betweencharging periods. The charge control circuits 104 and 106 measures thecapacitor charge voltage and protects the capacitors from charging todamaging voltage levels. The charge control circuits do this by shuntingthe solar panels output away from the capacitor(s) when the voltagereaches an ideal voltage (described in more detail below). The chargecontrol circuits re-connect the solar panels when the capacitor voltagefalls below the ideal voltage. In FIG. 6, the capacitive networks 108and 110 are used to store solar energy collected during the daylight. Atnight or during low light level conditions, the capacitor networksprovide enough energy to keep the clock and control circuitry powered(without interruption) until the solar panel can provide a recharge. Asa result, the capacitor networks must be sized accordingly.

The DC-DC converter 112 converts the capacitor voltages to a usablevoltage for the load 116. Similarly, DC-DC converter 114 converts thecapacitor voltages to a usable voltage for the timer and controlcircuitry 118. The DC-DC converters 112 and 114 receive energy from boththe solar panels 100 and 102 and capacitive networks 108 and 110 duringdaylight and from only the capacitive networks 108 and 110 duringnighttime. The energy stored in the capacitive network 106 keeps thecontrol circuitry powered indefinitely by using most of the availableenergy in the capacitors (even down to low voltages). The DC-DCconverter 112 also provides a regulated voltage output at theappropriate level for a given load. The timer and control circuitry 118may include an LCD display for showing the time of day and theprogramming of times at which power is provided to the load. The timerand control circuitry 118 also may include a user interface for the userto customize the operation of the system.

FIG. 7 is a block diagram illustrating another embodiment of the presentinvention. FIG. 7 is similar to FIG. 5, with the addition of aperipheral device 46. A peripheral device 46 can be powered in the samemanner as the circuitry 40. A peripheral device can be controlled by thecircuitry 40, or by any other desired manner. The peripheral device 46may be comprised of any desired device that can work with a capacitivelypowered system. In one example, the load may be a remote access pointand the peripheral device may be a wireless communication apparatus,such as a cellular telephone apparatus. In this example, the wirelesscommunication apparatus allows a user to remotely program or control thesystem. In addition, the wireless communication apparatus can be used toprovide system status to a remote user. For example, if used inconjunction with an access point, the wireless communication apparatuscan notify a user when the system requires attention. The wirelesscommunication apparatus can also provide alarms to notify a user ofdetected faults or other conditions. In another example, a peripheraldevice is an optical sensor. An optical sensor can be used to allow auser to manually operate the system from a distance.

FIG. 8 is a block diagram illustrating another embodiment of the presentinvention. In the embodiment shown in FIG. 8, the capacitive network 32is charged using a fuel cell 35. One advantage of this embodiment isthat the power to the system is not dependent on sunlight. Onedisadvantage, compared to using a solar panel, is that a fuel storagedevice will have to be periodically replenished by a user. In anotherembodiment, a system can use both solar panels and a fuel cell toprovide power to the capacitive network 32. Other embodiments are alsopossible. For example, a wind generator or other power source describedabove could be used as a source of energy to charge the capacitivenetwork.

FIG. 9 is a block diagram showing another embodiment of a system with anaccess point, router or other load. FIG. 9 shows a block diagram of asystem 50 that is similar to the systems described above, with acapacitive network for the DC-DC converter, user interface, andtimer/clock circuitry. A second solar panel and charging circuitsupplies power to battery 32B, which provide power to the access point,router or other load 18.

FIG. 10 shows a block diagram of a system 50 where an access point,router or other load 18 is powered by both a capacitive network 32A andbatteries 32B. In this example, the access point, router or other loadcan rely on battery power when no power is available from the capacitivenetwork, which will increase the life of the batteries.

In the preceding detailed description, the invention is described withreference to specific exemplary embodiments thereof. Variousmodifications and changes may be made thereto without departing from thebroader spirit and scope of the invention as set forth in the claims.The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

While the present system and method has been disclosed according to thepreferred embodiment of the invention, those of ordinary skill in theart will understand that other embodiments have also been enabled. Eventhough the foregoing discussion has focused on particular embodiments,it is understood that other configurations are contemplated. Inparticular, even though the expressions “in one embodiment” or “inanother embodiment” are used herein, these phrases are meant togenerally reference embodiment possibilities and are not intended tolimit the invention to those particular embodiment configurations. Theseterms may reference the same or different embodiments, and unlessindicated otherwise, are combinable into aggregate embodiments. Theterms “a”, “an” and “the” mean “one or more” unless expressly specifiedotherwise. The term “connected” means “communicatively connected” unlessotherwise defined.

When a single embodiment is described herein, it will be readilyapparent that more than one embodiment may be used in place of a singleembodiment. Similarly, where more than one embodiment is describedherein, it will be readily apparent that a single embodiment may besubstituted for that one device.

In light of the wide variety of possible wireless network devicesavailable, the detailed embodiments are intended to be illustrative onlyand should not be taken as limiting the scope of the invention. Rather,what is claimed as the invention is all such modifications as may comewithin the spirit and scope of the following claims and equivalentsthereto.

None of the description in this specification should be read as implyingthat any particular element, step or function is an essential elementwhich must be included in the claim scope. The scope of the patentedsubject matter is defined only by the allowed claims and theirequivalents. Unless explicitly recited, other aspects of the presentinvention as described in this specification do not limit the scope ofthe claims.

1. A method of operating a network device comprising: providing one ormore solar panels; storing energy from the one or more solar panels inone or more capacitors; providing control circuitry operatively coupledto the network device and to the one or more capacitors; using theenergy stored in the one or more capacitors to provide power to thenetwork device; and configuring the control circuitry to prevent thenetwork device from depleting energy stored in the one or morecapacitors below a critical level so that the control circuitry willhave enough energy available to sustain circuit operation, includingcritical logic operation and timekeeping operation, during time periodswhen the energy stored in the one or more capacitors is insufficient tomaintain operation of both the control circuitry and the network deviceduring a period of time in which there may be limited amounts of solarenergy for charging the capacitors back to a fully operational level. 2.The method of claim 1, wherein the charging of the one or morecapacitors is at least partially disabled when the voltage of the one ormore capacitors reaches a threshold voltage.
 3. The method of claim 1,wherein the network device is powered without using power from anon-photovoltaic power source such as a chemical battery.
 4. The methodof claim 1, further comprising using a DC-DC converter to step thecapacitor voltage up or down to provide a desired steady voltage levelto the network device, even as the capacitor voltages fall.
 5. Themethod of claim 1, wherein the control circuitry is programmable by auser to activate the network device at predetermined intervals anddurations.
 6. The method of claim 1, wherein the one or more capacitorscomprises first and second separate capacitive networks, wherein thefirst capacitive network provides power to the control circuitry, andthe second capacitive network provides power to the network device.